The present invention relates to a locking device for a flap or door of a motor vehicle, and, more particularly, to a locking device having a lock cylinder, an additional bolt and a spring-loaded detent member.
DE 3,018,733 C2 shows a locking device which affords a high degree of security against break-ins. Nevertheless, in the known arrangements, the additional bolt can be actuated solely by the key operation of the lock cylinder, which is coupled mechanically both to the lock and rigidly to the bolt, when the lock cylinder is brought into its mechanically secured position or rotated out of this again by the key.
A spring-loaded detent member complementary with a closing member of the flap or door prevents the lock cylinder from being brought into its mechanically secured position when the flap or door is open. Prelocking preceding the closing of the flap or door and additional securing of the locking device are therefore impossible.
DE 3,018,733 C2 describes a purely mechanical arrangement in which there is also no provision of any adjusting element of a central-locking system for the flap lock or door lock.
A comparable arrangement with an additional bolt, in which there are, on the one hand, a central-locking adjusting element for the lock and, on the other hand, in addition to the neutral key withdrawal position of the lock cylinder allowing only the use of the lock-adjusting element, a mechanically secured position which likewise allows the key to be withdrawn, is supplied as special equipment for the boot lid of vehicles of the Mercedes-Benz 126 type (S-class).
In the mechanically secured position of the lock cylinder, the special equipment and also other known vehicles with central locking do not provide any possibility of unlocking the associated lock via a central-locking system. The disadvantage of this is that there is often the desire to have all the doors to the passenger space unlocked during travel, but at the same time to keep the boot space secured against unauthorized access.
Moreover, the additional bolt comes into operation only in the mechanically secured position. Here too, because of the detent member already mentioned, a prelocking of the lock with additional securing by the bolt is impossible. In contrast, the additional bolt is inoperative in the neutral key withdrawal position of the lock cylinder, in which the central unlocking and locking of the associated lock are also possible.
An object of the present invention is to provide a motor vehicle closure locking device with greater operating convenience, while at the same time ensuring an equally high degree of security.
This object has been achieved by the configuration of the additional bolt prestressed by a spring in the direction of the securing position and movable mechanically into its release position counter to the force of the spring by the lock cylinder via a linkage with a free-play connection.
Instead of the known kinematic coupling of the additional bolt of the lock cylinder, a free-play linkage is now provided between the two. Furthermore, the bolt is prestressed in a way known per se in the securing direction by a spring.
As in the past, the additional bolt can be brought mechanically into its release position by the key actuation of the lock cylinder. In the simplest embodiment, the additional bolt is held in the release position by the detent member counter to the force of its spring immediately upon opening of the flap or door the lock cylinder becoming free of any force because of the free-play connection in the linkage.
It is thereby now possible, without varying the release position of the additional bolt, to rotate the key out of an unlocking position back into a neutral key withdrawal position.
By virtue of the detent member already mentioned, the bolt is retained in the release position counter to the force of the spring prestressing it, even when the lock cylinder has been brought temporarily or permanently into its mechanically secured position, but the associated flap or door has not yet been closed. A prelocking of the locking device preceding the closing of the flap or door thereby also now becomes possible.
In a simple version, the detent member also performs the function of an ejector which pushes the closing member out of the receptacle assigned to it and which at the same time keeps the bolt in the release position.
Similar detent devices for spring-loaded pushbolts are also known elsewhere (DE 2,362,038 B2, DE 3,017,049 C2).
In a vehicle equipped with central locking, the free-play linkage arrangement now makes it possible also to actuate the additional bolt by means of a further adjusting element of the central-locking system independently of the associated lock cylinder, so that even in a "normal" central locking of the vehicle, which can, for example, also be controlled from the lock cylinders of the driver's or front-seat passenger's door (so-called multi-point operation), the additional bolt is now brought into its securing position and, with central unlocking, into its release position again.
The security already attained hitherto can thus be utilized in an extremely convenient way.
If the detent member is appropriately designed, under some circumstances it is possible to do without an additional detent pawl when the adjusting element can hold the spring force acting on the bolt before the flap or door is opened by the actuation of the lock.
However, advantageously, the linkage for actuating the additional bolt is assigned a detent pawl which, in the release position of the bolt spring-loaded in the securing direction, drops in and retains the latter; it can be lifted out again by means of the lock cylinder or the adjusting element, so that the spring prestressing the bolt in the securing direction then brings the linkage into the securing position again, provided that the flap or door is closed.